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I have a 120V/15A pressure washer that's tripping the breaker and its own built-in-to-the-cord GFCI under certain conditions.

All of the available outdoor receptacles are on a single 15A circuit, chained off a single GFCI receptacle. The breaker is a plain (not GFCI) breaker.

When plugged directly into the GFCI receptacle (two GFCI's right on top of each other), the pressure washer works fine. But when plugged into either of the other receptacles chained from it, or into a (suitably rated) extension cord from the GFCI outlet, it trips the breaker and the GFCI after about 5-10 seconds of use.

In case the total wire length was just causing a loss that made the borderline current capacity insufficient, I also tried running the extension from a 20A circuit inside (also GFCI protected; I don't have any 20A circuits that aren't), but that also tripped. This leads me to believe it might be something about having 2 GFCI's chained with some distance between them, possibly causing spurious trips. Is there some phenomenon by which this happens, and if so, is there a standard fix?

How do I solve this in a way that's safe and code-compliant?

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    It trips every GFCI it's been tried on, including its in-cord GFCI. That doesn't seem like a faulty GFCI, it can only be the appliance. The breaker trip may be due to a more serious problem, or it may be just sharing the circuit with other loads that together exceed 20A.
    – Harper - Reinstate Monica
    Commented Feb 27, 2022 at 4:37
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    if it doesn't trip whn a faulty appliance is connected, but only for downstream your GFCI recepticle is installed backwards ("supply" and "load" swapped)
    – Jasen
    Commented Feb 27, 2022 at 12:16
  • @Harper: That's not what I said. It trips every two-chained-GFCI setups except the one where they're directly on top of each other (its own in-cord GFCI plugged into the main GFCI receptacle), where it works fine.
    – R.. GitHub STOP HELPING ICE
    Commented Feb 27, 2022 at 15:58
  • @Jasen: Thats a good thought - I'll check it.
    – R.. GitHub STOP HELPING ICE
    Commented Feb 27, 2022 at 15:58
  • My first rule of troubleshooting is to eliminate any known faults or screwball setups that unnecessarily complicate matters. I'm not sure what you meant about chained GFCIs; I'd suggest running through the advice here to eliminate any redundant or overlapping GFCI protection in the walls. Can't do a thing about the cord.
    – Harper - Reinstate Monica
    Commented Feb 27, 2022 at 19:42

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Your pressure washer has a ground leak and the GFCI's are doing their job. It may be a very minor leak, if you plug into a non GFCI outlet GROUNDED FOR SURE and it works, you have confirmed your pressure washer has a ground leak. Remember that GFCI outlets don't provide over-current protection, only ground fault protection. I had a Treager grill that would often trip the GFCI outlet. I finally ended up plugging it into a grounded, but non-GFCI protected outlet and it worked fine. Def, not a recommended approach, but good for diagnostics.

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  • It does not trip its own GFCI when plugged directly into the other GFCI, only when there's some large distance between the two GFCIs (either in-wall wiring or extension cord). So it seems unlikely that this is the case.
    – R.. GitHub STOP HELPING ICE
    Commented Feb 27, 2022 at 15:56

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